Apparatus for molding pistons



March 11, 1952 w. M. VENNER ET AL 2,588,898

APPARATUS FOR MOLDING PISTONS Filed May 27, 1950 3 Sheets-Sheet 1 March 11, 1952 w. M. VENNER ET AL APPARATUS FOR MOLDING PISTONS Filed May 2'7, 1950 5 Sheets-Sheet 2 WIN/am M4 Vsnner.

Pergy L. Bowser.

fir TOE/VEYS March 11, 1952 w. M. VENNER ET AL 2,588,898

APPARATUS FOR MOLDING PISTONS Filed May 27, 1950 3 Sheets-Sheet 5 INVENTOEfi WWW/km /T Vanna/i Para 1,. ZOWSGI'.

HT TOE/V5 Y5 Patented Mar. 11, 1952 APPARATUS FOR MOLDING PISTONS William M. Venner, Ladue, and Percy L. Bowser, University City, Mo.

Application May 27, 1950, Serial No. 164,812

2 Claims. 1

This invention relates to an apparatus for molding pistons, and particularly aluminum and magnesium alloy trunk pistons. This application is a continuation of application Ser. No.

620,571, filed October 5, 1945, now abandoned, as A to common subject-matter. Processes and apparatuses of this character, adapted for this purpose, are disclosed in the following patents: No. 1,551,193, August 25. 1925; No. 1,952,199, March 27, 1934; No. 2,129,351, September 6, 1938; No. 2,204,407, June 11, 1940.

An apparatus of the character described in the above patents comprises generally a pair of mold sections formed externally to shape the outside of the piston and a series of relatively collapsible core sections formed to shape the inside of the piston. In the apparatus of the character described in the above-noted patents the piston is cast with the head up and the gate is therefore at the top, and mechanism is provided for shifting the mold sections and the cores of the molds manually, hydraulically, pneumatically, or by cam mechanism.

Aluminum and magnesium alloys have relatively high crystallization shrinkages and coefllcients of expansion. A trunk piston embodies a head of relatively thick cross section and a skirt of relatively thin cross section. Where such a piston is cast with the head up and with the gate at the top, crystallization shrinkage is first compensated for in the skirt drawing from the metal in the head and the latter is then compensated for by drawing from the metal in the gate. More or less complete compensation for crystallization shrinkage finally in the head is indicated by a dropping of the gate in the center and coloration of that gate. The molder can therefore determine by observation when crystallization shrinkage has been compensated for. There is, however, also shrinkage due to the high -oo-efiicient of expansion of aluminum and magnesium alloys. The thin skirt will, of course, chill first followed by chilling of the head and finally followed by chilling of metal in the gate. Where the alloy is cast over a core usually collapsible in form which must be withdrawn after casting, the skirt will contract on the core materially before it begins to contract atthe head part. If, of course, the metal contracts on the core before the core is withdrawn to such extentas to seize the core, then it will be impractical or impossible to withdraw the core so that usually the casting must be brought to such a high temperature as to ruin it before it canbe withdrawn from the core. Where the core is apart 01a machine that of course represents great difiiculties. Such conditions are not so outstanding where the piston is cast with the head down because in such a case, the gate will extend along the skirt and will remain in molten or plastic condition perhaps even after the head has set. A proceeding, however, in which the piston is cast with the head up has great advantages over a proceeding in which the piston is cast with the head down because the former permits the casting to be performed in a machine.

We want to observe here that it is not so important to time the opening of the outside mold for unless that mold has parts going into the casting, which is very rare, it may be left closed an extended period after the metal has set because any shrinkage will be away from the mold and moreover the mold is made up of halves. The important consideration in casting a piston employing a core, particularly casting with the head up, is to release or extract the core from the casting as soon as possible in order to prevent any seizure of the casting on the core. The practice, therefore, is to watch the gate closely and as soon as crystallization shrinkage has been substantially compensated for, indicated by the appearance of the gate, the core is immediately withdrawn; thereafter the mold can be opened in a more or less leisurely fashion determined by the speed with which the casting operation is to be completed. Of course, the core should not be withdrawn too early because if that is done, the casting will be ruined. It should be really withdrawn at the right time.

The above will show the disadvantage of an apparatus for casting a piston with the head up and with the gate on top, and thereafter inverting the mold with its core in order to take the cores out by an upward movement. Even if the gate is closely observed, there is liability in two directions: first, if the mold is inverted too soon even before crystallization shrinkage of the head has been compensated for, the casting will be deficient, if not ruined; second, if, however, the mold with its core is inverted for too long a period after casting, then the skirt may seize the core and render it difiicult and even impossible to extract the same without ruining the casting. This will show the importance of always maintaining a mold core assembly with the gate up at all times but withdrawing the cores from the bottom thereby avoiding the two above possibilities mentioned.

' In view of the fact that the metal must be set after pouring, it has been possible for a single molder to operate a number of mold assemblies, and these are arranged adjacent a supply of molten metal, with the molder stationed between the molds and the supply, and for this purpose the molds are arranged side-by-side facing the source of supply. This, however, not only takes up space but requires that the molder direct practicall his entire attention visually and manually to one mold assembly while pouring, requiring the molder to distract his attention from the other mold assembly in which the metal may be setting.

- One of the objects of this invention, therefore, is to provide an apparatus for molding pistons in which a plurality of mold assemblies is arranged adjacent a supply of molten metal with the molder between the supply and the mold assemblies; but the apparatus is such that the molder, while pouring, can have the mold assembly, in which the metal is setting, under close observation.

Another object is to provide an apparatus of the character described in which the floor space required is materially reduced.

Further objects will appear from the detail description, taken in connection with the accompanying drawings, in which will be described and shown an illustrative embodiment of this invention. It is to be understood, however, that various changes maybe made in details, within the scope of the appended claims, without departing from the spirit of this invention.

In the drawings, Figure 1 is a plan view, generally diagrammatic in form, embodying this invention;

Figure 2 is a detail plan-of the mold assembly of Figure 1, again somewhat diagrammatic in form;

Figure '3 is a front view of the mold assembly again somewhat diagrammatically in form;

Figure 4 is a plan of the top of the carrier with the molds omitted;

Figure 5 is a front view of the carrier; and

Figure 6 .is a plan showing flex ible operating connections to the mold-operating means.

Generally stated and in accordance with the illustrative embodiment of this invention, a plurality of piston molds, each provided with a gate at the top and with a core movable downwardly from the bottom, :are arranged adjacent a supply of molten metal with the molder stationed between the molds and the supply, :andpower operated mechanism under control of the molder at the molders station is provided for rapidly shifting the molds alternately and in succession contiguous the -molders station for pouring the metal into the .top of the mold away from the station for setting of the metal, then back to the station for removal of the casting from the top of the :mold. The molds are, however, so arranged that when one mold with its core is away from the 'molders station, it is with its gate within theunobstructed view of the molder at the station 'atjwhich the molder is pouring the mold from its core at that station.

The apparatus comprises :a carrier 10, which is supported for movement on asub-base I00, a plurality of piston molds -l l, I I0, arranged oppositely on the carrier,-and means 40, for mounting the carrier in for movement on the subbase I00 to permit shifting of the molds alternately and in succession contiguous to the molders stations for pouring of the :metal "into the top of the mold and away from the station forsetting of the-metal, then back .to the station for removal of the casting from the top of the mold. Means 42-41 is provided for moving the carrier to so position the molds. The molds may comprise sections, together with means for moving the sections relatively. Flexible operating connections 88, may be provided for the moldoperating means, and where they are of the fluid-operated type, whether hydraulic or pneumatic, these flexible operating connections may be in the form of hose.

Referring now to the accompanying drawings,

and particularly to Figures 1 and '2, I0 designates a carrier on which is mounted a pair of molds or mold assemblies designated as H and H0 and which are arranged oppositely on the carrier. Each mold or mold assembly comprises a base 12 supported on the carrier by uprights l3. Mounted to slide laterally on the base [2 are a pair of mold sections l4 so as to be movable to the open and closed positions, with the mold sections when closed forming agate IS. A pair of cylinders it provided with pistons (not shown) are connected by rods I! to the mold sections, and each of these cylinders is provided with fluid connections 18 and 19, respectively. Another cylinder 20 is supported .by a bracket 2| from the base 112 and is provided with .a piston (not shown) connected with a rod 22, andthe cylinder is further provided with .fluid-conne'ce tions 23 and 24. The rod 22 is "connected withthe central part of a core (not shown) within the mold sections M, while therside core parts (not shown) are connected to levers 25 mov ng in slots 26 on the base.

The parts so far described, with theiexception of the carrier :10, may be of any suitable construction as shown in the various patents enumerated above. In molds of the character do scribedand as shown (in the patents enumerated, the mold is providedwith a :gate at the top, with a center core which moves downwardly from the bottom, with side cores movable into the-space previously occupied by the center core and with mold sections which move laterally to open the mold. As shownin these ,patents, the various parts of the mold :and of the core may beeperated by "fluid pressure or manually. .It is also to :be understood that .in the broadest aspectsiof this invention the :mold sections, "as well as the core sections or parts, may be operated manually. The coremayfurther be a'3-partcore or a-.5-part core, as :is alsoxsh'own in the above-enumerated patents.

Referringtnow tofigures 3,4,, and 5, the carrier 10 is mounted on rollers 40 mounted on brackets 4| arranged on the fioor or on a flanged subbase so that the carrier rests on the rollers within the flange Hi I. This carrier may be shiftedrotatably in any suitable manner and by any suitable mechanism other than herein described. With this particular embodiment, the carrier 10 is .provided with a gear 42 :fixed thereon with which meshes a .rack '43 held against the .gear by .a roll 44 on a bracket '45 on the sub-base. This :racl:

is connected with a :rod '46 of a piston tinot shown) working ma cylinder ATsupportedonthe cfloor or on theisub-base. This 'cylinderis'tprovided with fluid-connections '48 and for hydraulic or pneumatic fluid, leading from a 4-way valve 50 on the sub-base of "any suitable construction, and to. which the fluid is supplied by a connection "51. This valve is ,provided with a stem 52 "having a :head 53 "connected #by' *5'4 with an upstanding arm- 55 1011' ha rock. shaft :56 on the sub-base provided withrapedalstl and 58. The head 53 is also provided with a pin 59 working in an arcuate recess 60 in one end of a lever 6| pivoted at 62 on bracket 63 on the floor or on the sub-base. The arcuate recess terminates with shoulders 64 and 65 for engagement with the pin 59. The other end of the lever has a slot 66 engaging the pin 6'! on the rack 43. .The bracket 45 may be pivoted at 450 on the floor or on the sub-base and is engaged by a bar 68 moving in guide brackets on the sub-base. This bar may be adjusted lengthwise by an adjusting nut H screwed into the bracket 10 and provided with a lock nut 12.

Assummg the carrier to be in the position shown in Figures 2 and 3 at which time one of the mold assemblies is adjacent to and near the molders station, indicated at S of Figure 1, the procedure of shifting the carrier to bring the opposite mold assembly in a position for pouring is as follows:

The molder will depress the left treadle 5! thereby shifting the valve 50, Figure 4, through the connections 56, 55, 53, and 52. This will admit fluid through the connection 48 to the cylinder 41, causing its piston to move to the left, Figures 2 and 4, causing the rack 43, by engagement with the gear, to shift the entire carrier 10 through 180. In doing so, the lever Bl will be carried along with the rack and cause the shoulder 64 to engage the pin 59 so as to shift the head 53 and thereby the valve rod, 52 in order to close the valve. The carrier will therefore come to rest after rotation of 180. In order to shift the carrier back, the molder will depress the right treadle 58, which, by the connections previously described, will cause the valve to admit fluid to connection 49 and to the left end of the cylinder 41 so as to move the rack 43 back to the position shown in Figure 4, and at the end of the 180 rotation of the carrier the lug 65 will engage the pin 59 to again close the valve.

Referring again to Figure l in connection with Figure 3, it will be seen that the molders station S is between a mold assembly II and a source of supply of molten metal M, while the opposite mold assembly H0 will be opposite the mold assembly I l but in the direct line of vision of the molder at his station. The molder will fill his ladle from the supply M and pour the metal into the mold assembly ll. After pouring is completed the molder will ste on the left pedal 51, causing the carrier 40 to rotate inorder to shift the mold assembly ill] to the position contiguous the molders station while the mold assembly I l is now moved away from the molders station. The molder will then pour the metal into mold assembly I I0 (assuming it to be empty). The procedure then is as before, the molder now depressing the right pedal 58 after he has completed pouring of the mold assembly I I0. Whenever a mold assembly such as II and H0 arrive contiguous the molder, he will shift the various mechanisms to open the mold, collapse the core, and remove the piston.

Assuming in Figure 1 that the mold assembly II is adjacent the station S and that the metal in mold assembly H0 is setting, the molder, in opening the mold assembly ll, collapsing its cores removing the casting, and subsequently closing the mold assembly and expanding the cores followed by pouring, will at all times have the mold assembly H0 under his direct observation as it is directly opposite. Accordingly, any disturbance in the proper functioning of the mold assembly H0 will be always under direct observation. This is important because the functioning will be noted by the dropping of the gate and the change of color of the metal in the gate. This feature therefore is of great advantage in securing efficient and reliable metallurgical functioning of the entire apparatus. Moreover, since the mold in which the metal has set is moved back to the station for the removal of the casting, the same molder is able to further check upon the functioning of the entire process and apparatus. All of this can be accomplished by a single molder under whose control is the entire functioning of the apparatus.

The time allowed for the molder to flll his ladle from the source of supply M is very short, so that .even if the molders attention is then distracted, thereafter while he is pouring the mold at the molders station, he can observe what is taking place in the gate of the mold diametrically opposite. It should be observed here that when the molder has stepped on treadle 58 or 51 after the completion of the pouring ofthe mold, the mold itself is rapidly moved by mechanism away from the molders station to a diametrically opposite position. In other words, the time required for a poured mold to travel from the molders station to the diametrically opposite position is accomplished in a short space of time so that actually the mold will be at the setting position during substantially the entire time required for setting. Likewise the travel of the mold from the setting position back to the molders station is accomplished rapidly by treadle control. This is again of importance because if the molder should observe something not functioning properly at the setting position, he can immediately shift that mold back to him. That is important because if the metal should solidify, the piston will be ruined and seize on the core unless the core is withdrawn. Actually, the center core can be withdrawn before complete solidification because the side cores remain in position, but can move towards one another upon shrinking of the metal.

Referring again to Figure 1, it will be seen that the mold assembly is presented for-pouring and again is disassembled directly contiguous the molder so that he need only move a minimum amount, as distinguished from an arrangement in which the mold assemblies are arranged side-by-side. Furthermore, the floor space required is materially reduced by this arrangement of the mold assemblies.

It will be seen that where the mold and core operating mechanisms are mounted on a shiftable carrier, operating connections must be pro: vided in order to supply the mechanism with fluid, for instance such as hydraulic or pneumatic fluid. Referring now to Figure 6, in accordance with this invention, flexible operating connections in the form of a rubber hose are provided from conduits or pipes 8| from the main source of fluid supply to the fluid connections 82 to the mold and core operating mechanisms. Provision of this flexible hose furnishes means whereby the connections may be maintained during the shifting of the carrier without liability of breakage of connections or leakage. This is particularly true of the embodiment shown in Figure 3 because the rubber connections may be made directly to the pipes by suitable hose clamps and even cemented to provide for permanence.

It will thus be seen that the invention accomplishes its objects. An apparatus is provided in which the steps and the elements are so com- 7 bind as to work together inharmony to not only speed up production of aluminum magnesium alloy trunk piston castings, but also to avoid deiective castings-and seizure of the casting on the core. By casting the piston with the head up and the gate on to and with cores moving downwardly to withdraw them from the mold,-

it is possible to' shift the mold from pouring to setting position while the molder at the molding station can keep the gateoi the mold which has been poured under constant observation. This observation is not only permitted because the cores are out of the way and below the gate,- but even the connections to the mechanisms are so made as to" not obstruct that view. As soon as the condition of the .gate indicates that the alloy in the moldwhioh is in setting position away from the station, the mold can be quickly -moved back to position where the inolde'r can quickly release the core. Thereafter, he can open the mold and remove the casting in a more or less leisurely fashion, depending more or less upon the speed of output desired.

The invention'having thus been described, what is claimed is:

1. An apparatus for molding trunk pistons of aluminum and magnesium alloys having relatively high crystallization shrinkages and 00- efiicients of expansion and embodying a head having arelativ'ely thick cross section and askirt 6f relatively thin cross section, or which amolde'r s station isarranged adjacent a's'u'pply or molten metal, comprising, a plurality of piston molds,- each shapedto cast the piston with the head up, each provided with agate at the top and with a core movable downwardly from the bottom, acarrier for said molds andtheir' respective cores which are maintained thereon with their gates up and with their cores below, said molds and their respective cores being arranged in diametrically spaced relation on said carrier so that when one mold and its core is at the molders station, the other mold and its core; will be away from that station but diametrically opposite the first mold and'its core" and with its g'ate' within the direct and unobstructed view of the molde'r at-the station while pouring the mold at that station, mechanism for opening and for closing each mold a-n'd f-or withdrawing and for replacing its core while at that station, means for mounting said carrier for' movement, and power-operated mechanism under control of the molder at the molders station for rapidly shift-' ing' said carrier and with it'said molds and their respective cores in synchronis'm while maintaining their relative positions with each mold arid its core to positions first contiguous the molders station for pouring or" the metal into the "top of the mold, second away from the station for setting of the metal, and third back to the station for" downward withdrawal of the core, opening of the" mold; removal of the casting from the top of the mold and closing of the mold and core for r'epouring.

2; An apparatus for molding trunk pistons of aluminum and magnesium alloys having relatively high crystallization shrinkage's and coeiiicin'ts of expansion and embodying a head h'av'in'ga relatively thick cross section and' a skirt of relatively thin cross section, in which a molders station is arranged adjacent a supply of molten me'taLconipiisirig, a plurality of piston molds, each shaped to cast the piston with the head up, each provided with agate at'the top and with a core movable downwardly from the bottom, a carrier for said molds and their respec' tive cores which are" maintained thereon with t-heir gates'up and with their cores below, said molds and their respective cores being arranged in diametricallyspaced relation on said carrier so that when one mold and its core isatthe molders station, the other mold and its core will be away from that station but diametrically oppo site the first mold and its core and with its gate within the direct and unobstructed view of the niolder' at the station while pouring the mold'at that station, mechanism for openingand for closingeach mold and for withdrawing and for replacing its c'ore while at that station,- and means for mounting said carrier for movement,

and-powcr-operated mechanism under controlof i the molder at the molders station for' rapidly shifting said carrier and with it said molds and their respective cores in synchronism while main taining their relative positions with each mold and its core to positions? first contiguous the molders station for pouring of the metal into the top or the m'old',.s'econ'd away from the station for setting of the metal, and third back to the station for downward withdrawal of the core, opening of the mold, removal of the casting from the top of the mold and closing of the mold and core for repouring, flexible operating connections to said mechanism but constructed to leave direct view of the molder at the molders station un-' obstructed of the gate or the moldwhen away from and opposite that station.

are of this patent-Z UNITED STATES PATENTS Number Name Date 1,266,825 Kra'lund .-.r- May 21; 1918' 1 ,493,911 Ladd r -l June 24, 1-924 21115375 S-ulpri'zio" Oct. 1,- 1935 2,204,407 Flammang et a-I. Julie I1, 1940 2 ,336,931 FGHOWS D86 14, 1943 2,409,12'1- Fritschle Oct. 3; 1946' 

